CAIRO/RIYADH (Reuters) – A Saudi-led coalition fighting in Yemen said on Wednesday it had exchanged prisoners with its Houthi opponents and also welcomed a pause in combat on the border, prompting hopes of a push to end the year-long war that has killed some 6,000 people.

Riyadh’s confirmation of a rare confidence-building measure in the conflict came a day after senior Yemeni officials said a delegation from the Houthis, who are allies of the kingdom’s arch foe Iran, was in Saudi Arabia for talks to end the war.

However, both the Saudi Arabian and Yemeni foreign ministers later said any formal negotiations to end the fighting could only take place under the auspices of the United Nations and must include Yemen’s internationally recognized government.

Riyadh and a coalition of Arab states entered Yemen’s civil war a year ago in an attempt to restore President Abd-Rabbu Mansour Hadi after the Houthis and forces loyal to former president Ali Abdullah Saleh ousted him from power.

The Saudi state news agency SPA said Yemeni tribal mediators had facilitated the exchange of a Saudi lieutenant captured by the Houthis for seven Yemeni prisoners held in the kingdom.

The agency gave no further details, but some Yemeni media have reported that the exchange happened on the border between the two countries earlier this week.

Quoting a Saudi statement, SPA also said: “The leadership of the coalition forces welcomed the continuation of a state of calm along the border … which contributes to arriving at a political solution.”

After meeting his Gulf Arab and Yemeni counterparts, Saudi Foreign Minister Adel al-Jubeir said he backed U.N. special envoy Ismail Ould Cheikh Ahmed’s efforts to resolve the crisis based on U.N. resolution 2216, which calls on the Houthis to return power to Hadi’s government.

However, he added in a news conference that the lull was important to deliver aid and medical supplies to people in northern regions of Yemen. Yemeni Foreign Minister Abdelmalek al-Mekhlafi said the talks in Saudi Arabia were “on the intelligence level about prisoners and other issues”, adding that peace talks could only happen in accordance with the U.N. resolution.

“This is the only way forward with political negotiations. Anything else is operational and not political,” Mekhlafi said after the meeting with his Gulf Arab counterparts in Riyadh.